mirror of https://github.com/jackc/pgx.git
142 lines
2.6 KiB
Go
142 lines
2.6 KiB
Go
package pgtype
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import (
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"fmt"
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"io"
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"strconv"
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"github.com/jackc/pgx/pgio"
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)
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// CID is PostgreSQL's Command Identifier type.
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//
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// When one does
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//
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// select cmin, cmax, * from some_table;
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//
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// it is the data type of the cmin and cmax hidden system columns.
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//
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// It is currently implemented as an unsigned four byte integer.
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// Its definition can be found in src/include/c.h as CommandId
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// in the PostgreSQL sources.
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type CID struct {
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Uint uint32
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Status Status
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}
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// ConvertFrom converts from src to dst. Note that as CID is not a general
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// number type ConvertFrom does not do automatic type conversion as other number
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// types do.
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func (dst *CID) ConvertFrom(src interface{}) error {
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switch value := src.(type) {
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case CID:
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*dst = value
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case uint32:
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*dst = CID{Uint: value, Status: Present}
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default:
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return fmt.Errorf("cannot convert %v to CID", value)
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}
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return nil
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}
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// AssignTo assigns from src to dst. Note that as CID is not a general number
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// type AssignTo does not do automatic type conversion as other number types do.
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func (src *CID) AssignTo(dst interface{}) error {
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switch v := dst.(type) {
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case *uint32:
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if src.Status == Present {
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*v = src.Uint
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} else {
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return fmt.Errorf("cannot assign %v into %T", src, dst)
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}
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case **uint32:
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if src.Status == Present {
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n := src.Uint
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*v = &n
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} else {
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*v = nil
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}
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}
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return nil
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}
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func (dst *CID) DecodeText(r io.Reader) error {
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size, err := pgio.ReadInt32(r)
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if err != nil {
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return err
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}
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if size == -1 {
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*dst = CID{Status: Null}
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return nil
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}
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buf := make([]byte, int(size))
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_, err = r.Read(buf)
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if err != nil {
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return err
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}
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n, err := strconv.ParseUint(string(buf), 10, 32)
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if err != nil {
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return err
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}
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*dst = CID{Uint: uint32(n), Status: Present}
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return nil
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}
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func (dst *CID) DecodeBinary(r io.Reader) error {
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size, err := pgio.ReadInt32(r)
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if err != nil {
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return err
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}
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if size == -1 {
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*dst = CID{Status: Null}
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return nil
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}
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if size != 4 {
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return fmt.Errorf("invalid length for cid: %v", size)
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}
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n, err := pgio.ReadUint32(r)
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if err != nil {
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return err
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}
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*dst = CID{Uint: n, Status: Present}
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return nil
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}
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func (src CID) EncodeText(w io.Writer) error {
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if done, err := encodeNotPresent(w, src.Status); done {
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return err
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}
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s := strconv.FormatUint(uint64(src.Uint), 10)
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_, err := pgio.WriteInt32(w, int32(len(s)))
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if err != nil {
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return nil
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}
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_, err = w.Write([]byte(s))
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return err
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}
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func (src CID) EncodeBinary(w io.Writer) error {
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if done, err := encodeNotPresent(w, src.Status); done {
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return err
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}
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_, err := pgio.WriteInt32(w, 4)
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if err != nil {
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return err
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}
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_, err = pgio.WriteUint32(w, src.Uint)
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return err
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}
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